The purpose of this research is to determine the extent of the chronic pulmonary effect produced by occupational exposure to toluene diisocyanate (TDI) and to determine what levels of exposure are safe. Cohorts of workers are being followed with exposure to medium and low level exposures of TDI. The rate of decrement of pulmonary function (FVC and FEV1.O) is being determined. In addition, more detailed pulmonary function evaluation is being conducted.